Such pumps are already well known, particularly in the aeronautics field in which they allow self-regulated pumping of a control fluid for different hydraulic devices.
More particularly, in such pumps there is a slide face having at least two ports, including a suction port and a discharge port, a barrel rotating against this slide face, a set of pistons sliding in cylinders with a reciprocating motion corresponding to the suction function when the piston rises in the cylinder and to the discharge function when it descends.
This pump moreover comprises drive means to rotate this barrel in relation to the slide face. These means are made up essentially of a rotary shaft coupled to the barrel and pivoting in a fixed recess in relation to the slide face. This recess is made in a casing which also supports the slide face. It is to be noted that this recess can be located either on the periphery of the barrel or in certain cases at its center. In any case, it is necessary that the rotation in relation to the wall of the recess be favored to prevent any jamming because, when such a pump operates, it brings about a resultant of forces of significant magnitute on the axis of rotation.
To accomplish this, the shaft is generally coupled to the recess through an antifriction bearing such as a needle bearing, for example.
This arrangement gives good results but the service life may not be long enough to meet all the application requirements of these pumps, particularly at very high rotating speeds and discharge pressures.
Furthermore, the geometry, determined by considerations relative to overall dimensions and weight, the different hydraulic parameters to be complied with, and noise levels, call for reduced dimensions for the bearing.
It is the object of the present invention to provide a hydraulic pump having structural features giving it a service life long enough to be acceptable in all technical fields and especially in the aeronautical field.
More precisely, the object of the present invention is to provide a hydraulic pump comprising:
a slide face in which are formed two ports, respectively the suction and discharge ports,
a casing supporting said slide face,
a barrel capable of pivoting, on the one hand around an axis perpendicular to the surface of said slide face in a bearing block integral with said support casing and, on the other hand, against said slide face, said barrel comprising a plurality of hollow cylinders each having an opening leading out onto the side of said barrel sliding on the surface of said slide face to move over said ports,
pistons sliding in a sealed manner respectively in each of said cylinders,
means for controlling, when a rotation is imparted to said barrel, on the one hand the movement of said pistons away from the opening of the cylinders in which they slide when this opening passes in front of the suction port and, on the other hand, the movement of said pistons toward the opening of said cylinders in which they slide when this opening passes in front of the discharge port, characterized in that it includes means for sequentially supplying the pressure prevailing in said cylinders on the given portion between said bearing block and the part of said barrel cooperating with said bearing block.
Other characteristics and advantages of the present invention will appear from the following description in connection with the illustrative drawings.